This invention relates to a tool assembly for connection to a drill string within a bore hole for oil and gas wells, and more particularly to a hydraulic stabilizer for such a tool assembly which may be expanded radially to engage the inner periphery of the bore hole or casing defining the bore hole.
Heretofore, with certain well tools, such as cutting tools for cutting pipe or casing previously installed within a well, it is desirable to center and stabilize the cutting tools particularly within large diameter casing. When the stabilizer is fixed for rotation with the mandrel and cutters, the cutting blades on the tool tend to impact or vibrate continuously against the inner periphery of the casing. Thus, it is highly desirable that any stabilizer be stationary when set within the casing so that the mandrel and associated tool may rotate relative to the stabilizer which acts as an anchoring means to center the mandrel and minimize any lateral movement thereof while permitting relative rotation.
Several types of radially expandable shoes have been employed for stabilizing or centralizing various types of tools within a well bore. For example, U.S. Pat. No. 3,098,534, dated July 23, 1963 shows a drill string for directional drilling having a mandrel thereon and an outer tube on the mandrel carrying a hydraulically actuated shoe which may be radially expanded and contracted. The shoe is adapted particularly for directional drilling and is mounted on one side of the drill string for deflection of the drill bit while permitting relative rotation of the mandrel.
U.S. Pat. No. 3,370,657, dated Feb. 27, 1968 likewise shows a stabilizer for a well tool having radially expandable shoes adapted to engage the inner periphery of the well bore while permitting rotation of the drill string and bit. The shoes are carried or mounted on a carriage which is movable downwardly for setting the shoes and movable upwardly for retraction of the shoes. The shoes are utilized particularly for radial shifting of the bit in directional drilling.
Other references show other various types of centralizers or stabilizers such as in U.S. Pat. No. 3,664,416, dated May 23, 1972; U.S. Pat. No. 3,273,645, dated Sept. 20, 1966; and U.S. Pat. No. 4,557,327, dated Dec. 10, 1985. However, these additional references do not show a centralizer or stabilizer mounted on a mandrel and being radially expandable to engage the inner periphery of an adjacent casing or the like in fixed relation while permitting relative rotation of the mandrel.